No brakes after pad/disc change

[matth444]

Hi guys

Have been fitting some new discs and pads to the Micra. Took everything off, had trouble retracting the piston so removed the piston and used some fine sandpaper to get the rust off, then retracted fine. put everything back together and now I have no brakes. Engine off, pedal is stiffer and clunks halfway down travel, and engine on, drops straight to the floor with little persuasion. any ideas? my best guess is some air somewhere because I didn't bleed the system before taking out the pistons, but guy at local car shop said I didn't need to. Also worth mentioning I did lose half a jars worth of fluid or thereabouts through accidentally pouring some out of the piston bores, so may have dropped below the minimum line in the reservoir, though that is topped up now.

im not a mechanic by any means so this may be obvious to some but like to try stuff myself. this is getting exceptionally frustrating!

 

[Chie]

I would say aor on the system. Try bleeding them. Possibly all 4 corners incase you have air elsewhere

Sent from my SM-F926B using Micra Sports Club mobile app

 

[vexorg]

Might need a new piston if you've been too rough, it needs to be very smooth to seal. A refurb caliper is usually the easiest way.

Did you properly bleed them all after?
Two man method is a must for problem brake, there should be a clear flow out with no bubble, and keep the reservior topped up enough.

 

[matth444]

I don't THINK I've been too rough - did a very quick go with some 1200 and 2000 wet and dry on the rust patches. If I've taken too much off the pistons it would be leaking right? To be honest im not surprised it's ended up like this though - was planning on buying some refurbed ones but thought it was worth a shot fixing em myself before that!

I'll give bleeding them properly a go when I have time. I'll follow the guide in the Haynes manual. Cheers for your help guys, I'll try remember to post an update when I do!